Predictions in Ungauged Basins: Promise and Progress (Proceedings of symposium S7 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 303, 2006, 371-381.

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Distributed rainfall–runoff analysis in a flow regulated basin having multiple multi-purpose dams

TAKAHIRO SAYAMA¹, YASUTO TACHIKAWA¹, KAORU TAKARA¹ & YUTAKA ICHIKAWA²

1 Disaster Prevention Research Institute, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan

sayama@flood.dpri.kyoto-u.ac.jp

2 Department of Urban and Environmental Engineering, Kyoto University, Yoshida Honmachi, Kyoto, 606-8501, Japan

Abstract This paper presents hydrological predictions and flood safety assessment in a flow regulated basin with multi-purpose dams. A distributed rainfall–runoff prediction system is developed by incorporating a dam reservoir operation model into a physically based rainfall–runoff model for simulating a highly regulated Japanese river basin, the Yodo River basin (7281 km²), in which eight multi-purpose dams are currently operated. The test simulation for typhoon events verified that the system can simulate complex flood control operations such as preliminary release, peak attenuation, and water level maintaining. Following the test simulation, the developed system was applied to assess the flood safety level of the basin. The numerical experiments indicated that the basin is safe for a rainfall event of a 100-year return period due to the newly constructed multi-purpose dams, whereas it was safe only for a rainfall event of a 30-year return period in 1960.

Key words dam model; distributed rainfall–runoff model; flood safety level; flow regulation; human impact; peak attenuation; Yodo River basin

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